By way of background, conventional PIVC's include a catheter assembly, typically having a catheter hub and a catheter tube extending distally thereof, and a needle assembly mounted together in an over-the-needle fashion. The needle assembly typically includes a needle hub or support and a needle cannula extending distally thereof and, in a ready position of the PIVC, extending through the catheter tube to expose a sharp tip thereof distal of the tube and used to penetrate tissue for insertion of the catheter tube within the vascular system of a patient. Once the catheter tube is disposed within the vasculature, the needle cannula is withdrawn proximally from the catheter assembly and the catheter assembly remains in fluid communication with the vasculature. The PIVC may also include a protector to enclose at least the tip of the needle cannula, if not the entire cannula, after use. A PIVC with a protector may be referred to as a safety catheter.
The catheter hub typically has an open proximal end adapted to receive a male luer taper into the interior cavity of the catheter to establish a fluid connection between the patient's vasculature and the luer taper. The proximal end may also be provided with external ears or the like to secure the luer taper in the catheter hub, such as when the luer taper is coupled with a male luer lock collar or nut to form part of a male luer lock such as of a connector of an administration set or the end of a syringe, or the like. Under normal conditions, after withdrawal of the needle cannula and before a luer taper is inserted into the catheter hub, blood immediately starts flowing through the catheter tube and into the interior cavity of the catheter hub. In typical catheter hub designs, the proximal end of the catheter hub is in open communication with the catheter tube through the interior cavity such that, if not attended to in a timely manner, blood can flow into the catheter hub and spill into the surrounding environment. To limit blood flow into the catheter hub, medical personnel typically apply digital pressure near the insertion site to occlude blood flow into the catheter tube. An administration set or a syringe is then coupled to the catheter assembly for introducing fluids into, and/or withdrawing blood from, the patient.
Various designs of catheter assemblies have been proposed for controlling or limiting blood flow by inclusion of a hemostasis seal within the interior cavity or at the proximal end opening of the catheter hub, to block fluid flow between the proximal end of the catheter hub and the catheter tube. In these designs, the hemostasis seal provides for passage of the needle cannula therethrough in the ready position of the PIVC, but seals against the flow of blood to or out of the proximal end of the catheter hub upon proximal withdrawal of the needle cannula. The hemostasis seal is adapted to be opened by insertion of a luer taper into the catheter hub to allow flow of fluid between the luer taper and the catheter tube.
While various designs of catheter assemblies with hemostasis seals have been proposed, none seems to have garnered commercial acceptance. Thus, improvements are considered necessary in order to address drawbacks of existing proposals.